1. Field of the Invention.
The present invention relates to the treatment of liquids, including waste liquids and, particularly, to apparatus of the type having a propeller which draws air or other gas into an elongated leg for discharge into the liquid on rotation of the propeller within the liquid.
2. Description of the Prior Art.
Aeration devices for the treatment of liquid, and particularly water, are known to the prior art. Such treatment may be employed to encourage aerobic bacteria in the treatment of waste water or in the treatment of water bodies generally to make it more potable or suitable for food production. Ice control is also another application for which it may be desirable to "treat" water by aeration.
Known liquid aeration treatment systems include those generically classified in four categories: diffused air; surface aerator; jet aerator; and rotors. Each of these systems has applications in which they have particular advantages. Each also has applications in which they are not particularly suitable.
A further type of aerator, of which the present invention is an improvement, is known to the prior art. This type of aerator employs a propeller and motor with a leg extending between the motor and propeller. The leg includes a shaft coupled to the motor which drives the propeller. An outer housing often surrounds the shaft.
Units of the type described in the paragraph immediately above are supported, in any desired manner, with the motor out of the liquid being treated and the leg extending below the liquid surface. An air intake allows rotation of the propeller to draw air into the leg to be discharged generally at or through the propeller. In all systems of this type known to the inventor, the outer housing (when it exists) is used to provide support for the shaft with the shaft being hollow to provide a flow of air from the inlet to the point of discharge. While these types of systems have proven effective, the length of the shaft provides a difficult alignment problem necessitating the use of the outer housing (or other similar structure) to support the shaft and minimize its deflection. The use of a hollow driving shaft to provide an air passageway between surface and point of discharge compounds this deflection problem while limiting the airflow capacity of the device.